Grade in this incredibly good, looking at score

I believe the answer is:

sight-reading

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'grade in this incredibly good' is the definition.
The definition suggests a singular noun but the answer is not.

'looking at score' is the wordplay.
'looking' becomes 'sight' (I've seen this before).
'at score' becomes 'reading' (I can't justify this - if you can you should believe this answer much more).
'sight'+'reading'='SIGHT-READING'

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I've seen this clue in The Telegraph.

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